package org.apache.lucene.xmlparser.builders;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.queryParser.ParseException;
import org.apache.lucene.queryParser.QueryParser;
import org.apache.lucene.search.Query;
import org.apache.lucene.xmlparser.DOMUtils;
import org.apache.lucene.xmlparser.ParserException;
import org.apache.lucene.xmlparser.QueryBuilder;
import org.w3c.dom.Element;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * UserInputQueryBuilder uses 1 of 2 strategies for thread-safe parsing:
 * 1) Synchronizing access to "parse" calls on a previously supplied QueryParser
 * or..
 * 2) creating a new QueryParser object for each parse request
 */
public class UserInputQueryBuilder implements QueryBuilder {

	QueryParser unSafeParser;
	private Analyzer analyzer;
	private String defaultField;
	
	/**
	 * This constructor has the disadvantage of not being able to change choice of default field name
	 * @param parser thread un-safe query parser
	 */
	public UserInputQueryBuilder(QueryParser parser) {
		this.unSafeParser = parser;
	}

	public UserInputQueryBuilder(String defaultField, Analyzer analyzer) {
		this.analyzer = analyzer;
		this.defaultField = defaultField;
	}
	
	/* (non-Javadoc)
	 * @see org.apache.lucene.xmlparser.QueryObjectBuilder#process(org.w3c.dom.Element)
	 */
	public Query getQuery(Element e) throws ParserException {
		String text=DOMUtils.getText(e);
		try {
			Query q = null;
			if(unSafeParser!=null)
			{
				//synchronize on unsafe parser
				synchronized (unSafeParser)
				{
					q = unSafeParser.parse(text);
				}
			}
			else
			{
				String fieldName=DOMUtils.getAttribute(e, "fieldName", defaultField);
				//Create new parser
				QueryParser parser=createQueryParser(fieldName, analyzer);
				q = parser.parse(text);				
			}
			q.setBoost(DOMUtils.getAttribute(e,"boost",1.0f));
			return q;
		} catch (ParseException e1) {
			throw new ParserException(e1.getMessage());
		}
	}
	
	/**
	 * Method to create a QueryParser - designed to be overridden
	 * @param fieldName
	 * @param analyzer
	 * @return
	 */
	protected QueryParser createQueryParser(String fieldName, Analyzer analyzer)
	{
		return new QueryParser(fieldName,analyzer);
	}

}
